Medical imaging

ABSTRACT

The present invention relates to methods of assessing or obtaining an indication of the presence of a cognitive disorder by analysing microstructural changes in regions of the brain. The invention particularly relates to methods of assessing or obtaining an indication of the presence of types of dementia, for example Alzheimer&#39;s disease, by analysing changes in minicolumns in regions or layers of the cortex of the brain or of the whole brain.

CROSS-REFERENCE

This application is the US national phase under 35 U.S.C. § 371 ofinternational application PCT/GB2016/050982, filed Apr. 7, 2016, whichclaims priority to Great Britain application 1505940.5, filed Apr. 8,2015.

FIELD OF INVENTION

The present invention relates to methods of assessing or obtaining anindication of the presence of a cognitive disorder by analysingmicrostructural changes in regions of the brain. The inventionparticularly relates to methods of assessing or obtaining an indicationof the presence of types of dementia, for example Alzheimer's disease,by analysing changes in minicolumns in regions of the cortex of thebrain.

BACKGROUND OF THE INVENTION

Diagnosis and treatment of dementia is an increasing problem given theageing population. Currently dementia affects over 830,000 people in theUK. However, given the difficulties in accurate diagnosis of thesedisorders, the actual proportion of people affected by these disordersmay be much greater.

There are many recognised forms of dementia. These include Alzheimer'sdisease (AD), cerebrovascular disease (CVD), frontotemporal dementia(FTD) and dementia with Lewy Bodies (DLB). Mild Cognitive Impairment(MCI) is considered to be a precursor to dementia.

Current methods of diagnosis usually depend on clinical screening toolsin the form of cognitive tests and assessment of behavioural symptoms.Currently, a standard structural brain MRI may often be requested inorder to seek evidence of a qualitative (i.e. visually apparent)reduction in hippocampal volume, enlargement of ventricles and theappearance of enlarged sulcal folding of the cerebral cortex. Thisassessment is subjective and non-specific, and therefore whilst itprovides additional evidence, it is not diagnostic in itself.Differential diagnosis of AD from CVD is usually dependent on theclinical assessment of disease course, with progressive cognitivedecline being gradual in the case of AD in contrast to ‘stepwise’ (rapiddrops interrupted by ‘plateaus’ of relative stability). Clearly this isalso subjective and open to interpretation.

The current cognitive test is usually the MMSE (mini-mental state exam)for which ‘healthy’ is often considered to be a score >24, MCI 21-24 anddementia 20 or less. However, these boundaries are changeable and alsoopen to interpretation. Some consider a score of <30 to be compatiblewith MCI. An additional test, the MoCA (Montreal cognitive assessment)has recently been found to be sensitive to CVD-type cognitive changesthat may be missed by MMSE. However, it does not provide a differentialdiagnosis.

Currently, Alzheimer's disease and other forms of dementia can onlydefinitively be diagnosed by post-mortem histology. The exactbiochemical processes are not sufficiently understood to offer methodsthat are an accurate alternative to post-mortem examination.Additionally, most existing measurements of neuropathology in dementiadepend on assessment of plaques, tangles or individual cells andsynapses, which are at the microscopic level and thus cannot be detectedusing conventional non-invasive brain imaging.

Early diagnosis of these conditions is particularly important foreffective clinical intervention to halt or slow the progression of thedisease, since the neuropathological changes that occur in dementia arethought to start occurring significantly earlier than the appearance ofsymptoms.

An additional problem in this field of medicine is that, despite someshared risk factors, the clinical course and potential treatmentstrategies differ between different types of dementia, for example ADand CVD. Cognitive testing gives an indicator of decline in mentalfunction, but with currently available tools it is difficult todiscriminate between different types of dementia. Therefore, it isparticularly important from a clinical perspective to be able todifferentiate between different types of dementia so that theappropriate course of action and treatment can be taken.

Currently biomarker detection depends on: i) invasive methods for CSF orblood (which carry risk to patients); ii) invasive methods for imagingmolecular markers in the brain (which carry risk to patients such thatthey cannot often be repeated); or iii) non-invasive brain imagingmethods which are based on statistical number-crunching of populationsamples using standard volumetric MRI or more recent texture analysis ofstructural MRI (such as T1 or T2, for example).

The invention addresses this need for a non-invasive and accurate way ofassessing the presence and/or severity of cognitive disorders includingdementia, by assessing microstructural changes in the cortex.

SUMMARY OF THE INVENTION

The minicolumn microcircuit is considered to be the fundamental unit inthe organisation and function of the cortex of the brain. Whilst it hasbeen reported that minicolumn spacing of cells in human associationcortex is reduced in normal aging (i.e. minicolumn thinning) (Chance S.A.; Casanova M. F.; Switala A. E.; Crow T. J.; Esiri M. M. Minicolumnthinning in temporal lobe association cortex but not primary auditorycortex in normal human ageing. Acta Neuropathologica 111(5):459-64(2006)), few microanatomical measures have been reliably correlated withcognitive measures in ageing and Alzheimer's disease (AD), particularlyin the early stages of degeneration, such as MCI. Recently, Chance etal. (Chance S. A.; Clover L.; Cousijn H.; Currah L.; Pettingill R.;Esiri M. M. Micro-anatomical correlates of cognitive ability anddecline: normal ageing, MCI and Alzheimer's disease. Cerebral Cortex21(8):1870-8 (2011)) reported that minicolumn changes in two areas ofthe cortex (the association cortex in the planum temporale (BA22) andprimary auditory cortex (BA41)) were correlated with pre-mortemcognitive scores (mini-mental state examination and verbal fluency) inboth MCI and AD brains. However, whereas the association cortex showed astrong correlation with cognitive function, in the primary auditorycortex this relationship was an epiphenomenon of overall brain atrophy.Therefore it remains unknown whether there are specific patterns ofchanges in the brains of patients with cognitive disorders such asdementia. In particular, whether distinct patterns of change occur indifferent types of dementia remains unknown.

The inventors have found that signature patterns of microanatomicalchanges within certain regions of the brain associated withneuropathological conditions do indeed exist and correlate withcognitive ability and decline. These signature patterns can be used asbiomarkers or predictors of the presence and also severity/staging ofcognitive disorders in a living subject, as described in the presentinvention. A distinct advantage of the present invention is that thecharacteristic patterns of brain ‘signatures’ described herein aredetectable in life, and with existing non-invasive techniques which arefar safer than other potential methods of detection currently based oninvasive methods.

These patterns of microstructural changes occur in specific regions ofthe brain and the pattern of changes observed in different regions ofthe brain is specific to particular cognitive disorders. These patternscan therefore be used as a biomarker to assess the likelihood of whethera subject has a particular cognitive disorder, and if the presence ofsuch a disorder is indicated, the methods of the invention can also beused to assess the severity of the cognitive disorder.

Given that these signature patterns are specific to particular cognitivedisorders, these methods may also be used for discriminating betweendifferent types of cognitive disorders which can be difficult todistinguish using currently available diagnostic tools.

These signature patterns can be quantified non-invasively using dataderived from MRI scanning and imaging methods applied to the brains ofsubjects, using different MRI methods including but not limited todiffusion tensor imaging (DTI), Fine Structure Analysis (fineSA™, see:http://www.acuitasmedical.com/technology.php) and other MRI acquisitionmethods. The data derived from these imaging studies can then becompared to the predicted pattern of change determined from patientswith confirmed diagnoses of such conditions. This comparison of acquireddata from a subject of interest with the modelled data derived frompatients with confirmed diagnoses will then aid in the assessment anddiagnosis of different types of dementia or other cognitive disorders inliving subjects, including early stages of dementia.

The inventors have also found that diffusion MRI measures, particularlyDTI, can be used to assess minicolumn structure in the brain. Whilst DTImeasures in the white matter have been conducted in other studiesindicating changes in AD, these studies have only assessed the whitematter of the brain. DTI is standard as an analysis of white matter inthe brain, providing information regarding axonal fibre tracts, forexample. In contrast, the analysis of DTI measures in the cortical greymatter is entirely different, with a different interpretation (sinceminicolumns do not exist in the white matter). Thus the invention alsoprovides a new way of assessing minicolumn structure in the brain, whichmay be useful in the assessment of cognitive diseases in a clinicalsetting.

A further advantage of this invention is that the target, i.e. theminicolumn (including axon bundles and dendrites), is unique as a‘mesoscopic’ structure that has a periodic, directional structure at ascale that can be detected as a signal using new, high resolutionimaging methods (such as DTI, Fine Structure Analysis or other MRIacquisition methods), in contrast to existing microscopic measurementsof neuropathology in dementia which depend on assessment of plaques,tangles or individual cells and synapses at the microscopic level whichcannot be observed using conventional non-invasive brain imaging.

The invention may be particularly useful in providing a method fordiagnosing or staging Alzheimer's disease and other dementias usingsignature patterns of microstructural brain changes.

The invention may also be applied to other cognitive disorders orneurological conditions where there are structural changes in the brain.Such cognitive disorders include autism, schizophrenia, bipolardisorder, epilepsy, dyslexia, Down's syndrome, Parkinson's disease,amyotrophic lateral sclerosis, Huntington's disease, multiple sclerosis,prion disease, depression, obsessive-compulsive disorder, and attentiondeficit hyperactivity disorder (ADHD).

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows minicolumn width (μm) in different areas for controls(CTRL), AD, and FTD patients. Both in the dIPFC and PHG the CTRL groupis significantly different from the AD and FTD group. In the PT, theCTRL group is significantly different from the AD group.

FIG. 2 shows minicolumn width (μm) in different areas for CVD, AD, andFTD patients. CVD is only significantly different from FTD in the dIPFC.

FIG. 3 shows minicolumn width (μm) in different areas for CTRL's and theCVD group. The CTRL group is significantly different than the CVD groupfor both dIPFC and PHG.

FIG. 4 shows minicolumn width (μm) in different areas (dIPFC, PHG, PT,HG and Fusi) for CTRL's, MCI, AD and CVD groups.

FIG. 5 shows MMSE score for different groups.

FIG. 6 shows NART score for different groups.

FIG. 7 shows the resulting map with predictive group centroids andterritories from the discriminant analysis conducted using minicolumnwidths from five brain regions: PFC, HG, PT, PHG, and Fusi to comparecontrols, CVD and AD.

FIG. 8A shows a graph of data from post-mortem non-dementia brains(including controls, MS and autism) demonstrating that wider minicolumnsare associated with a lower perpendicular diffusion measure.

FIG. 8B shows pilot post-mortem imaging reveals an increasedperpendicular diffusion measure in dementia consistent with minicolumnthinning (p=0.05, n=4 AD vs 4 controls).

FIG. 8C shows that the DTI biomarker has a graded effect reflecting thedegree of AD pathology values increase with greater severity of ADpathology. (Data are mean values for 4 control subjects and individualsub-regions values from 4 probable AD brains sub-regions PHG, HG, and PTshow a characteristic pattern of differences).

FIG. 9 shows pilot in vivo cortical diffusion data (mean diffusivity)from 6 subjects. Each graph shows cortical diffusivity (MD) for 5regions from a single subject. Top row: graphs from 2 Control subjects,Mid row: graphs from 2 MCI subjects, Bottom row: 2 AD subjects. The PHGfeature in the pattern (orange contrast) differentiates controls fromMCI, the Fusi feature (yellow contrast) differentiates AD from MCI.

FIG. 10 shows a flow chart illustrating an algorithm for early anddifferential diagnosis of dementia and other brain disorders.

FIG. 11 shows an example of a multi-region analysis of corticaldiffusion data from a single control and single AD case with a list ofbrain regions. Some example regions of interest for differentiatingdiagnoses are circled.

FIG. 12 shows data from an in vivo comparison of 18 AD and 18 controlsubjects which shows a combination of angle of minicolumnar deviationwith volume segmentation data summarised for whole brain. Clearseparation of the groups is illustrated with only a single anomalouscontrol case found in the large separation zone delineated by dashedlines.

FIG. 13 shows a comparison of in vivo data on autism and controls usingone of the new DTI measures related to minicolumn angle of deviation.

DETAILED DESCRIPTION OF THE INVENTION

It is therefore an object of the invention to provide a method ofassessing or obtaining an indication of the presence of a cognitivedisorder in a subject by analysing microstructural changes in regions ofthe brain.

It is another object of the invention to provide a method of assessingor obtaining an indication of the presence of types of dementia, forexample Alzheimer's disease, by analysing microstructural changes inregions of the cortex of the brain.

In one embodiment, the invention provides a method of obtaining anindication of the presence of a cognitive disorder in a subject, themethod comprising the steps of correlating:

-   (a) one or more diffusion MRI measurements of minicolumn-based    parameters obtained from the subject's brain, or values derived    therefrom; and-   (b) the presence or absence of a cognitive disorder in the subject,    thereby obtaining an indication of the presence of a cognitive    disorder in the subject.

The invention also provides a method of obtaining an indication of thepresence of a cognitive disorder in a subject, the method comprising thestep of: (a) determining from one or more diffusion MRI measurements ofminicolumn-based parameters obtained from the subject's brain, or valuesderived therefrom, an indication of the presence of a cognitive disorderin the subject.

Preferably, the determining step comprises comparing the diffusion MRImeasurement(s) of the minicolumn-based parameter(s) obtained from thesubject's brain, or values derived therefrom, with correspondingdiffusion MRI measurements or values derived therefrom obtained from oneor more control subjects with defined cognitive disorders, therebyobtaining an indication of the presence of a cognitive disorder in thesubject.

The invention also provides a method of obtaining an indication of thepresence of a cognitive disorder in a subject, the method comprising thesteps of comparing:

-   (a) one or more diffusion MRI measurements of minicolumn-based    parameters obtained from the subject's brain, or a value derived    therefrom; and-   (b) the corresponding measurement(s) or value(s) obtained from a    control subject without a cognitive disorder,    wherein if the measurement or value obtained in step (a) is one    which is positively correlated or directly proportional to the    likelihood of the subject having a cognitive disorder, an increase    in the measurement or value obtained in step (a) compared to the    corresponding measurement or value in step (b) is indicative of the    subject having a cognitive disorder; and wherein if the measurement    or value obtained in step (a) is one which is negatively correlated    or inversely proportional to the likelihood of the subject having a    cognitive disorder, a decrease in the measurement or value obtained    in step (a) compared to the corresponding measurement or value in    step (b) is indicative of the subject not having a cognitive    disorder.

The invention also provides a method of obtaining an indication of theprognosis of a subject with a cognitive disorder, the method comprisingthe steps of comparing:

-   (a) one or more diffusion MRI measurements of minicolumn-based    parameters obtained from the subject's brain, or values derived    therefrom, with-   (b) corresponding previously-obtained diffusion MRI measurements    obtained from the subject's brain, or corresponding values derived    therefrom,    wherein a change in the measurement or value obtained in step (a)    compared to the corresponding measurement or value obtained in    step (b) is indicative of a change in the prognosis for the subject.

If the measurement or value obtained in step (a) is one which ispositively correlated or directly proportional to the severity of thecognitive disorder, an increase in the measurement or value obtained instep (a) compared to the corresponding measurement or value in step (b)is indicative of a decline in the prognosis for the subject, and adecrease in the measurement or value obtained in step (a) compared tothe corresponding measurement or value in step (b) is indicative of animprovement in the prognosis for the subject.

If the measurement or value obtained in step (a) is one which isnegatively correlated or inversely proportional to the severity of thecognitive disorder, a decrease in the measurement or value obtained instep (a) compared to the corresponding measurement or value in step (b)is indicative of a decline in the prognosis for the subject, and anincrease in the measurement or value obtained in step (a) compared tothe corresponding measurement or value in step (b) is indicative of animprovement in the prognosis for the subject.

The invention also provides a method of obtaining an indication of theefficacy of a drug which is being used to treat a cognitive disorder ina subject, the method comprising the steps of:

-   (a) comparing first and second diffusion MRI measurements of    minicolumn-based parameters obtained from the subject's brain, or    values derived therefrom, wherein the drug has been administered to    the subject in the interval between the taking of the first and    second MRI measurements,    wherein if the measurement or value obtained in step (a) is one    which is positively correlated or proportional to the severity of    the cognitive disorder, an increase in the second measurement or    value obtained in step (a) compared to the first measurement or    value is indicative of the lack of efficacy of the drug; and a    decrease in the second measurement or value obtained in step (a)    compared to the first measurement or value is indicative of the    efficacy of the drug.

If the measurement or value obtained in step (a) is one which isnegatively correlated or inversely proportional to the severity of thecognitive disorder, an increase in the second measurement or valueobtained in step (a) compared to the first measurement or value isindicative of the efficacy of the drug; and a decrease in the secondmeasurement or value obtained in step (a) compared to the firstmeasurement or value is indicative of the lack of efficacy of the drug.

In yet another embodiment, the invention provides a method of obtainingan indication of the presence of a specific cognitive disorder in asubject, the method comprising the steps of correlating:

-   (a) one or more minicolumn-based parameters or values derived    therefrom from one or more regions of the brain of the subject, with-   (b) the presence of a specific cognitive disorder in a subject,    thereby obtaining an indication of the presence of a specific    cognitive disorder in the subject.

The invention also provides a method of obtaining an indication of thepresence of a specific cognitive disorder in a subject, the methodcomprising the step:

-   (a) determining from one or more minicolumn-based parameters or    values derived therefrom from one or more regions of the brain of    the subject an indication of the presence of a specific cognitive    disorder in the subject.

Preferably, the determining step comprises comparing the one or moreminicolumn-based parameters or values derived therefrom from one or moreregions of the brain of the subject with corresponding minicolumn-basedparameters or values derived therefrom from one or more regions of thebrains of one or more control subjects with defined cognitive disorders,thereby obtaining an indication of the presence of a specific cognitivedisorder in the subject.

The invention also provides a method of obtaining an indication of thepresence of a specific cognitive disorder in a subject, the methodcomprising the steps of:

-   (i) comparing one or more minicolumn-based parameters or values    derived therefrom from one or more regions of the brain of the    subject, with-   (ii) a reference set of minicolumn-based parameters or values    derived therefrom from corresponding regions of the brains of    control subjects with specific cognitive disorders,    thereby obtaining an indication of the presence of a specific    cognitive disorder in the subject.

The invention further provides a method of obtaining an indication ofthe presence of a specific cognitive disorder in a subject, the methodcomprising the steps of comparing:

-   (i) a signature pattern obtained from one more minicolumn-based    parameters or values derived therefrom from one or more regions of    the brain of the subject, with-   (ii) a reference signature pattern obtained from minicolumn-based    parameters or values derived therefrom from one or more regions of    the brains of control subjects with specific cognitive disorders,    thereby obtaining an indication of the presence of a specific    cognitive disorder in the subject.

The invention also provides a computer-implemented method of obtaining ameasurement of a minicolumn-based parameter in a region of the brain ofa subject, the method comprising the steps of:

-   (a) comparing one or more diffusion MRI measurements obtained from a    region of the brain of the subject or values derived therefrom, with-   (b) a reference set of diffusion MRI measurements or values derived    therefrom from corresponding regions of the brains of control    subjects with defined minicolumn-based parameters,    thereby obtaining a measurement of the minicolumn-based parameter in    the region of the brain of the subject.

The invention also provides a computer-implemented method of deriving asignature pattern from one or more minicolumn-based parameters in aregion of the brain of a subject, the method comprising the steps of:

-   (a) comparing one or more diffusion MRI measurements obtained from a    region of the brain of the subject, or values derived therefrom,    with a reference set of diffusion MRI measurements or values derived    therefrom from corresponding regions of brains of control subjects    with defined minicolumn-based parameters, thereby obtaining    measurements of one or more minicolumn-based parameters in the    region of the brain of the subject, and-   (b) deriving a signature pattern from the measurements of the one or    more minicolumn-based parameters in the region of the brain of the    subject.

In a particularly preferred embodiment of the methods of the invention,the one or more minicolumn-based parameters are obtained by diffusionMRI.

As used herein, the term “cognitive disorder” refers to any mentalhealth disorder that affects learning, memory, perception, and/orproblem solving.

In preferred embodiments of the invention, the cognitive disorder may beany form of dementia.

Preferably, the cognitive disorder is selected from the group consistingof (i) Alzheimer's Disease (AD), (ii) cerebrovascular dementia (CVD),(iii) mild cognitive impairment (MCI), (iv) frontotemporal dementia(FTD), and (v) dementia with Lewy Bodies (DLB).

In other embodiments, the cognitive disorder may be a neurologicaldisorder associated with changes in normal brain structure, preferably aneurological disorder selected from the group consisting of (i) autism,(ii) multiple sclerosis (MS), (iii) epilepsy, (iv) amyotrophic lateralsclerosis (ALS) and (v) Parkinson's disease.

In other embodiments, the cognitive disorder is preferably aneuro-psychiatric disorder, most preferably selected from the groupconsisting of schizophrenia, bipolar disorder, dyslexia, Down'ssyndrome, Huntington's disease, prion disease, depression,obsessive-compulsive disorder and attention deficit hyperactivitydisorder (ADHD). In some preferred embodiments, the cognitive disorderis an autism spectrum disorder.

As used herein, the term “diffusion MRI” refers to any magneticresonance imaging (MRI) method which measures the diffusion process ofmolecules, preferably water molecules, in biological tissues. DiffusionMRI may also be referred to as diffusion tensor imaging (DTI).

Preferably, the diffusion MRI measurement is selected from perpendiculardiffusivity, mean minicolumn diffusivity, radial diffusivity, minicolumnwidth, mean diffusivity, fractional anisotropy, grey matter density andangle of columnar deviation, or a value derived therefrom.

Perpendicular diffusivity is the component of the diffusion occurring inthe principle diffusion direction that is perpendicular to the radialdirection across the cortex. This can be measured by multiplying themain eigenvector (V1) by the value of its corresponding eigenvalue (L1),then resolving this into its components. The value of the componentperpendicular to the radial direction across the cortex is theperpendicular diffusivity.

Minicolumn diffusivity is the combination of the components of diffusionacross multiple diffusion directions that are perpendicular to theradial direction across the cortex. This can be measured by taking theeigenvalues from all three eigenvectors and combining the components ofthe eigenvalues that are perpendicular to the radial direction acrossthe cortex in order to create a mean value.

Mean diffusivity is a measure of the total diffusion occurring in avoxel. It is calculated by finding an average of the three eigenvalues(i.e. (L1+L2+L3)/3). For the analysis presented herein, the value ofeach of these is calculated for each voxel individually. A weightedaverage of the values along each cortical profile is then calculated togive the mean diffusivity.

Radial diffusivity is the component of the diffusion occurring in theprinciple diffusion direction that is parallel to the radial directionacross the cortex. This can be measured by multiplying the maineigenvector (V1) by the value of its corresponding eigenvalue (L1), thenresolving this into its components. The value of the component parallelto the radial direction across the cortex is the radial diffusion. Forthe avoidance of any doubt, it should be noted that the term “radialdiffusion” has also become a term which is often applied to whitematter, referring to the amount of diffusion perpendicular to theprimary diffusion direction (a definition which is dependent on theintrinsic diffusion signal in any voxel). However, that is not the sameas the measurement as used herein, which specifically refers to theanatomical radial direction across the cerebral cortex (a definitionwhich is related to anatomy, specifically the expected radial directionof minicolumns).

Fractional anisotropy (FA) is a measure of the degree of anisotropy, ordirectional dependence, of a process, where zero represents isotropic orunrestricted diffusion, and 1 represents diffusion occurring along onlyone axis with total restriction along the other axes.

As used herein, the term “angle of columnar deviation” is usedinterchangeably with the terms angle of deviation, V1_angle and V1_angleof deviation. It is defined as the difference between the estimatedcolumnar direction which is the radial direction across the cortex, andthe direction of the main eigenvector (V1), expressed as an angle. Theangles of the other eigenvectors (V2, V3) relative to the estimatedradial direction across the cortex may also be used.

Individual structural MRI scans can be registered to a group averagetemplate and then segmented into white and grey matter density beforebeing smoothed. This results in images where each voxel contains anaverage grey matter density calculated over the surrounding voxels.

Diffusion MRI measurements are correlated with minicolumn width andminicolumn spacing. Particular types of diffusion MRI measurements, orvalues derived therefrom, may be directly proportional (positivelycorrelated) or inversely proportional (negatively correlated) tominicolumn width and minicolumn spacing.

Perpendicular diffusion and mean diffusivity are each inverselyproportional to minicolumn width and minicolumn spacing. Minicolumnwidth and minicolumn spacing are correlated within subjects withcognitive disorders. Therefore, perpendicular diffusion and meandiffusivity are increased in subjects with cognitive disorders such asAD when compared to normal control subjects without said cognitivedisorder. Perpendicular diffusion and mean diffusivity also increase asthe severity of the cognitive disorder increases.

In contrast, radial diffusivity, fractional anisotropy and grey matterdensity are each proportional to minicolumn width and minicolumnspacing. Minicolumn width and minicolumn spacing are correlated withcognitive disorders. Therefore, radial diffusivity, fractionalanisotropy and grey matter density are decreased in subjects withcognitive disorders such as AD when compared to normal control subjectswithout said cognitive disorder. Radial diffusivity, fractionalanisotropy and grey matter density also decrease as the severity of thecognitive disorder increases.

In embodiments wherein the diffusion MRI measurement or a value derivedtherefrom is previously-obtained or derived from a control subject, themeasurement or value derived therefrom may be obtained from a graph,look-up table, database or mathematical equation, or the like.

Examples of diffusion MRI measurements which are positively correlatedwith or are directly proportional to the likelihood of the subjecthaving a cognitive disorder or the severity of the cognitive disorderinclude: perpendicular diffusivity, and mean minicolumn diffusivity.

Examples of diffusion MRI measurements which are negatively correlatedwith or are inversely proportional to the likelihood of the subjecthaving a cognitive disorder or the severity of the cognitive disorderinclude: radial diffusivity, fractional anisotropy and grey matterdensity.

As used herein, the term “signature pattern” refers to a pattern,profile or fingerprint of one or more minicolumn-based parameters whichis characteristic of a specific cognitive disorder. This signaturepattern can be used to help to distinguish between specific cognitivedisorders. In its simplest form, the signature pattern may be a singleparameter, e.g. minicolumn width or minicolumn spacing.

In other embodiments, the signature pattern may be a mathematicalformula or equation or multi-parameter function which incorporates oneor more minicolumn-based parameters and optionally one or morenon-minicolumn-based parameters. The formula or equation or function maybe linear or non-linear, and may include squares or higher powers of theparameters.

Non-minicolumn-based parameters may include levels of specific proteinsin the brain or in certain brain regions, or parameters based on definedphysiological structures, e.g. plaque levels or protein tangles.

Other non-minicolumn-based parameters include those defined herein atMRI diffusion measurements or values derived therefrom.

In some embodiments, the invention provides a method of obtaining anindication of the presence or absence of a specific cognitive disorderin a subject, the method comprising the step of comparing:

-   (i) one or more minicolumn-based parameters or values derived    therefrom from one or more regions of the brain of the subject, with-   (ii) one or more reference sets of minicolumn-based parameters or    values derived therefrom from corresponding regions of the brains of    control subjects, wherein the reference sets are obtained from    control subjects with different specific cognitive disorders or    without specific cognitive disorders,    wherein if the minicolumn-based parameters or values derived    therefrom obtained from the subject are within the range of the    reference set of measurements or values derived therefrom from    corresponding regions of the brains of control subjects with a    specific cognitive disorder, then this provides an indication of the    presence of that specific cognitive disorder in the subject; and    wherein if the minicolumn-based parameters or values derived    therefrom obtained from the subject are within the range of the    reference set of measurements or values derived therefrom from    corresponding regions of the brains of control subjects without a    specific cognitive disorder, then this provides an indication of the    absence of that specific cognitive disorder in the subject.

In some embodiments, a reduction in the minicolumn width in theprefrontal cortex and parahippocampal gyrus compared to non-diseasedcontrols is indicative of the subject having CVD.

In other embodiments, a reduction in minicolumn width in all of thedIPFC (dorsolateral prefrontal cortex), PHG (parahippocampal gyrus), PT(planum temporale), HG (Heschl's gyrus—primary auditory region), andFusi (Fusiform gyrus) compared to non-diseased controls is indicative ofthe subject having Alzheimer's Disease.

In embodiments of the invention, the minicolumn-based parametersobtained from the subjects' brains are obtained by a neuro-imagingmethod.

In preferred embodiments of the invention, the minicolumn-basedparameters are measured using magnetic resonance imaging (MRI) of thebrain.

The minicolumn-based parameters may be measured directly from an MRIscan of the subject's brain or from MRI data previously-obtained fromthe subject's brain.

In some embodiments, the MRI measurement may be a value that is derivedfrom the individual brain MRI measurements using mathematical formulas,algorithms, databases and/or look-up tables.

In preferred embodiments, the value is derived from MRI measurementsobtained from the brain or from images of the brain.

In some embodiments of the invention, the minicolumn measurements areobtained by diffusion MRI.

In other embodiments, the minicolumn-based parameters are obtained usingT1 or T2 or T2* mapping or the MRI measurement may be a spectroscopicmeasurement of T1, T2, or T2* localised to the brain.

In some embodiments, the one or more measurements are preferablyobtained using the imaging methods described in WO2013/040086 (thecontents of which are hereby incorporated by reference) or FineStructure Analysis™ (fineSA™; Acuitas Medical) or other MRI acquisitionmethods.

In some embodiments of the invention, the minicolumn-based parametersused as the control (to which the measurements obtained in the subjectare compared) may be obtained histologically.

In other embodiments of the invention, the minicolumn-based parametersused as the control are obtained by the same method as theminicolumn-based parameters obtained from the subject.

As used herein, the term “minicolumn” is a vertical column through thecortical layers of the brain. Minicolumns may also be referred tointerchangeably as cortical minicolumns, microcolumns or corticalmicrocolumns.

The term “minicolumn” may either be understood to be the combination ofthe cell-dense core and cell-sparse peripheral neuropil spacesurrounding it or, in some circumstances, just the cell-dense core(defined by the cell bodies). Typically, it relates to the core andperiphery.

The minicolumn-based parameter may be a directly measurable feature ofthe minicolumn, preferably a microstructural or cytoarchitecturalfeature of the minicolumn.

Examples of directly measurable minicolumn-based parameters includeminicolumn width, minicolumn spacing, axonal fibre bundle width, axonalfibre bundle spacing, dendritic fibre bundle width, dendritic fibrebundle spacing, minicolumn core width, and minicolumn peripheralneuropil space.

Preferably, the minicolumn-based parameter is minicolumn width orminicolumn spacing.

The minicolumn-based parameter may also be one which is an indirectlymeasured or a derived feature. Such features may be correlated with orproportional to a directly measurable feature of the minicolumn andtherefore provide an indicator or biomarker of a directly measuredfeature of the minicolumn. Examples of indirectly measured or derivedminicolumn-based parameters include perpendicular diffusion, meandiffusivity or radial diffusivity, fractional anisotropy or grey matterdensity, as defined above. As discussed previously, these parameters arecorrelated with or proportional to parameters such as minicolumn width,and so provide an indicator or biomarker of minicolumn width.

Minicolumn width is defined as the width of the minicolumn core (seebelow) and half of the peripheral neuropil space (see below) on eitherside of it. The mean minicolumn width may be used, preferably inconjunction with a defined brain region.

Minicolumn width may be measured histologically as follows. Images aretypically acquired from a stained microscope section of the dissectedcerebral cortex (typically using a standard Nissl stain such as Cresylviolet). The image is automatically segmented to select neurons andnearest-neighbour measurements of clustering are applied to determinethe periodicity of columnar distribution. Segmentation is based on greylevel intensity of the digitized photo-micrographic image, withautomated shape and size thresholds for cell identification. Columnarorganization is calculated using the Euclidean distance minimum spanningtrees based on the cell centroids. These methods are described in ChanceS. A.; Casanova M. F.; Switala A. E.; Crow T. J.; Esiri M. M. Minicolumnthinning in temporal lobe association cortex but not primary auditorycortex in normal human ageing. Acta Neuropathologica 111(5):459-64(2006)] and [Chance S. A.; Clover L.; Cousijn H.; Currah L.; PettingillR.; Esiri M. M. Micro-anatomical correlates of cognitive ability anddecline: normal ageing, MCI and Alzheimer's disease. Cerebral Cortex21(8):1870-8 (2011)].

Minicolumn spacing is defined as the centre-to-centre spacing of theminicolumns, and so includes both the cell bodies of the neurons and theneuropil space. When based on the average minicolumn core and averageperipheral neuropil space across multiple minicolumns within a patch ofcerebral cortex, the mean centre-to-centre spacing is effectively thesame as the mean minicolumn width.

Minicolumn spacing may be measured histologically as follows. Images aretypically acquired from a stained microscope section of the dissectedcerebral cortex (typically using a standard Nissl stain such as Cresylviolet). The image is automatically segmented to select neurons andnearest neighbour measurements of clustering are applied to determinethe periodicity of columnar distribution. Segmentation is based on greylevel intensity of the digitized photo-micrographic image, withautomated shape and size thresholds for cell identification. Columnarorganization is calculated using the Euclidean distance minimum spanningtrees based on the cell centroids.

Minicolumn core width is defined as the part of the column that contains90% of the cell bodies. Minicolumn core width may be measured asfollows. Having identified the neuronal cell bodies, a computer programis able to identify the vertical centre of the cell dense core based onthe cell distribution and measure the width of the area containing 90%of the neuronal cell bodies.

Minicolumn peripheral neuropil space refers to the surrounding neuropilcontaining mostly neurite (mainly dendrites and axons) with very fewcell bodies, which along with the minicolumn core, makes up theminicolumn. Minicolumn peripheral neuropil space can be calculated bysubtracting the measure of the minicolumn core from the value of theminicolumn width.

Minicolumns consist of a vertical string of neurons, along with theassociated axons and dendrites. Multiple individual axons grouptogether, forming bundles as they descend from layers III to VI within,or closely adjacent to, the core of the minicolumn. Therefore, axonbundle spacings are thought to provide a similar measurement of thecolumnar organisation of the cortex to that provided by the measurementof minicolumn width.

Measurements of axonal bundle centre-to-centre spacing are made manuallyin image analysis software, using linear measurement tools. A sampleline of standard length is drawn across the centre of a digitalphoto-micrograph, perpendicular to the bundle direction in order toidentify the bundles to be measured. Only bundles intersecting this lineare measured, those that pass out of the plane of sectioning above orbelow the line are not included. Single axons or pairs of axons crossingthe line are not considered to constitute axon bundles for the purposesof this analysis. Bundles (>2 axons) are identified and their centresmarked (using a typical axon fibre or myelin stain such as sudan blackor Palmgren's silver stain). Bundle spacing measurements are then madefrom the centre of each bundle marked in this way to the centre of theadjacent bundle, for all bundles intersecting this line.

A variant of the technique based on horizontal sections (similar to thatdescribed below for dendrite bundles) is given in Di Rosa E.; Crow T.J.; Chance S. A. Axon bundle spacing in anterior cingulate cortex in thehuman brain. Journal of Clinical Neuroscience 15(12):1389-1392 (2008).Axon bundle width refers to the width of the axon bundles associatedwith each minicolumn.

After identifying the axon bundles as described for the measurement ofaxon bundle spacing, the width of the axon bundles is made usingstandard linear measurement tools in any suitable image analysissoftware. The edges of the bundles are marked at the point where theyintersect the horizontal line, and the bundle width is determined as thedistance between these two points. Edges of axon bundles aredistinguished by the change in intensity of staining from thebackground, which identifies the start of the more darkly stained axonbundle (using a typical axon fibre or myelin stain such as sudan blackor Palmgren's silver stain).

Dendrite bundles are the bundles of dendrites that extend vertically (inthe direction of the minicolumns) through the cerebral cortex. They arethe dendritic equivalent of axon bundles.

They can be measured in a similar way to axon bundles though often theyhave been measured differently, using horizontal sections of cerebralcortex which transect the dendrites. Individual dendrites are thereforeseen as individual points on stained sections and the bundle is measuredas a ‘cluster’ of these points based on their distribution within the2-dimensional section. The spacing of these bundles is then based on theInter-cluster distance′. This spacing may be either defined as the meandistance between the perimeters of neighbouring clusters or as the meandistance between the geometric centroids of the clusters. More detailsof such a technique are provided in Gabbott, P. L. and Stewart, M. G.(2012). Visual deprivation alters dendritic bundle architecture in layer4 of rat visual cortex. Neuroscience, 207 pp. 65-77.

Dendrite bundle width is the width of the bundle of dendrites thatextend vertically (in the direction of the minicolumns) through thecerebral cortex. This is the dendritic equivalent to axon bundle widthand may be measured in a similar way to axon bundles, but has often beenmeasured differently using horizontal sections (as described fordendrite bundle spacing, above). In this case, the dendrite ‘cluster’has a mean diameter which will constitute the dendrite bundle width.

In preferred embodiments of the invention, the minicolumn-basedparameter measurements are obtained from one or more different regionsof the brain, preferably two or more, three or more, four or more, fiveor more, six or more, seven or more, or eight or more different regionsof the brain, most preferably five or more different regions of thebrain. The term “one or more regions of the brain” includes the wholebrain.

In preferred embodiments of the invention, the minicolumn-basedparameters are obtained from or derived from one or more regions orlayers of the cortex of the brain. In preferred embodiments, theminicolumn-based parameters are obtained from one or more specificlayers of the cortex, preferably from cortical layer 3, cortical layer5, or cortical layers 3-6.

In more preferred embodiments, the parameters are obtained from corticallayers 3-6 since these also contain axon bundles which may be useful forDTI signal analysis.

Preferably, the brain regions are selected from the group consisting ofthe parahippocampal gyrus (PHG), fusiform gyrus (Fusi), dorsolateralprefrontal cortex area 9 (dIPFC), Heschl's gyrus (HG), planum temporale(PT), inferior parietal lobule (IPL), middle temporal gyrus (MTG) andprimary visual cortex (V1; area 17).

In some embodiments of the invention, the brain region is preferably thecortical grey matter.

In some preferred embodiments, the minicolumn-based parameters areobtained from or derived from 1, 2, 3, 4, 5, 6, 7 or 8 of the aboveregions.

In preferred embodiments of the invention where the method is used todistinguish between AD and CVD, the minicolumn-based parameters areobtained from or derived from one or more regions selected from thegroup consisting of the parahippocampal gyrus (PHG), fusiform gyrus(Fusi), dorsolateral prefrontal cortex area 9 (dIPFC), Heschl's gyrus(HG), and planum temporale (PT). In some preferred embodiments of theinvention where the method is used to distinguish between AD and CVD,the minicolumn-based parameters are obtained from all of these regions.Use of parameters obtained from or derived from all five of theseregions in the methods of the invention achieves >94% predictiveaccuracy for differentiating AD from CVD. In preferred embodiments ofthe invention where the method is used to obtain an indication of thepresence of Mild Cognitive Impairment (MCI), the minicolumn-basedparameters are obtained from or derived from one or more regions of thecortex of the brain, preferably from one or more regions selected fromthe group consisting of the parahippocampal gyrus (PHG), fusiform gyrus(Fusi; area 37), dorsolateral prefrontal cortex area 9 (dIPFC), Heschl'sgyrus (HG), planum temporale (PT), inferior parietal lobule (IPL),middle temporal gyrus (MTG) and primary visual cortex (V1; area 17). Insome preferred embodiments of the invention where the method is used toobtain an indication of the presence of Mild Cognitive Impairment, theminicolumn-based parameters are obtained from all of these regions.

In preferred embodiments of the invention where the method is used todifferentiate FTD from other dementias, the minicolumn-based parametersare obtained from or derived from one or more regions of the cortex ofthe brain, preferably from one or more regions selected from the groupconsisting of the parahippocampal gyrus (PHG), fusiform gyrus (Fusi),dorsolateral prefrontal cortex area 9 (dIPFC), Heschl's gyrus (HG),planum temporale (PT), inferior parietal lobule (IPL), middle temporalgyrus (MTG) and V1. In the most preferred embodiments of the inventionwhere the method is used to differentiate FTD from other dementias, theminicolumn-based parameters are obtained from all of these regions.

In some preferred embodiments, the cognitive disorder is Alzheimer'sDisease (AD) and the minicolumn based parameter measurements areobtained from or derived from one or more brain regions selected fromthe group consisting of:

(i) the banks of the superior temporal sulcus, entorhinal, isthmuscingulate, lateral occipital, lateral oribitofrontal, middle temporal,parahippocampal, parstriangularis, pericalcarine or posterior cingulateregion of the left-hand cortex; and

(ii) the banks of the superior temporal sulcus, cuneus, entorhinal,middle temporal, parahippocampal, paracentral or posterior cingulateregion of the right-hand cortex.

In other preferred embodiments, the cognitive disorder is Alzheimer'sDisease (AD) and the minicolumn based parameter measurements areobtained from or derived from the whole brain.

The regions of the brain defined herein are preferably as defined onBrodmann's cytoarchitectural organisation of the human cortex (Brodmann,1909). The equivalents may also be seen in Von Economo and Koskinas (VonEconomo C, Koskinas GN (1925) Die Cytoarchitektonik der Hirnrinde desErwachsenen Menschen. Springer, Berlin (Germany) (Translated by Dr LeeSeldon)).

The methods of the invention may also be used to distinguish othercognitive or neuro-psychiatric disorders, as defined below. When themethods of the invention are used to distinguish the disorders recitedbelow, the brain regions analysed should include one or more, morepreferably all, of the corresponding brain regions recited below:Autism: fusiform cortex, superior temporal sulcus, orbitofrontal cortex,dIPFC, inferior parietal cortex, primary visual cortex, primary auditorycortex

-   Schizophrenia: dIPFC, dorsomedial PFC, cingulate gyrus, superior    temporal gyrus, PHG-   Bipolar disorder: PHG, subgenual PFC, dIPFC, cingulate-   Epilepsy: entorhinal cortex, PHG-   Dyslexia: inferior parietal cortex, superior temporal gyrus-   Down's syndrome: superior temporal gyrus, PHG, dIPFC-   Parkinson's disease: entorhinal cortex, cingulate gyrus-   Amyotrophic lateral sclerosis: motor cortex-   Huntington's disease: motor cortex, cingulate gyrus-   Multiple sclerosis: motor cortex, cortical regions containing MS    lesions identified by MRI scan-   Prion disease: primary visual cortex, cortical areas showing    volumetric shrinkage contrasted with cortical area with no    discernible shrinkage-   Depression: dIPFC, dorsomedial PFC, cingulate gyrus-   Obsessive-compulsive disorder: cingulate gyrus, dIPFC, dorsomedial    PFC-   ADHD: orbitofrontal cortex, dIPFC, cingulate

The subject may be any animal, preferably a mammal, most preferably ahuman. In some embodiments, the subject may be one with a cognitivedisorder, preferably one with dementia.

In some embodiments, the subject is one which has: (i) Alzheimer'sDisease (AD), (ii) cerebrovascular dementia (CVD), (iii) mild cognitiveimpairment (MCI), (iv) frontotemporal dementia (FTD), or (v) dementiawith Lewy Bodies (DLB). Preferably, the subject has Alzheimer's disease,FTD, CVD, or MCI.

In other embodiments, the subject may be one with a neurologicaldisorder associated with changes in normal brain structure.

In some embodiments, the subject is one which has autism, multiplesclerosis (MS), epilepsy, amyotrophic lateral sclerosis (ALS),Parkinson's disease, schizophrenia, bipolar disorder, dyslexia, Down'ssyndrome, Huntington's disease, prion disease, depression,obsessive-compulsive disorder or attention deficit hyperactivitydisorder (ADHD).

In some embodiments, the subject is older than 1, 5, 10, 20, 30, 40, 50,60, 70, 80 or 90 years. In other embodiments, the subject is 5-100,10-100, 20-100, 30-100, 40-100, 50-100, 60-100, 70-100, 80-100 or 90-100years old. In other embodiments, the subject is 1-5, 5-10, 10-20, 20-30,30-40, 40-50, 50-60, 60-70, 70-80, 80-90 or 90-100 years old.

In some embodiments, the subject is not a foetus. The control subjectmay be a healthy subject or a non-healthy subject.

In some embodiments, the control may be defined as a non-diseasedcontrol, one without a cognitive disorder, a typically-developed controlor a healthy-aged control. Control subjects may alternatively be called“reference” subjects.

As used herein, the term “corresponding minicolumn-based parameters orvalues derived therefrom” refers to a parameter or a value which is madeon the same region of the brain as the one to which it is beingcompared, and preferably obtained under the same conditions

For example, the “corresponding minicolumn-based parameters” may referto a diffusion MRI measurement which is made on the same part of thebrain as the one to which it is being compared.

Preferably, the increase or decrease is a significant increase ordecrease (e.g. univariate ANOVA, P<0.05).

In preferred embodiments, the methods of the invention arecomputer-implemented methods. For example, the methods may beimplemented using software.

In a further embodiment, the invention provides a system or apparatuscomprising at least one processing means arranged to carry out the stepsof a method of the invention.

The processing means may, for example, be one or more computing devicesand at least one application executable in the one of more computingdevise. The at least one application may comprise logic to carry out thesteps of a method of the invention.

In a further embodiment, the invention provides a carrier bearingsoftware comprising instructions for configuring a processor to carryout the steps of a method of the invention.

EXAMPLES

The present invention is further illustrated by the following Examples,in which parts and percentages are by weight and degrees are Celsius,unless otherwise stated. It should be understood that these Examples,while indicating preferred embodiments of the invention, are given byway of illustration only. From the above discussion and these Examples,one skilled in the art can ascertain the essential characteristics ofthis invention, and without departing from the spirit and scope thereof,can make various changes and modifications of the invention to adapt itto various usages and conditions. Thus, various modifications of theinvention in addition to those shown and described herein will beapparent to those skilled in the art from the foregoing description.Such modifications are also intended to fall within the scope of theappended claims.

The disclosure of each reference set forth herein is incorporated hereinby reference in its entirety.

Example 1: Microstructural Analysis of Post-Mortem Brain Tissue Methods

TABLE 1 Demographic summary human subjects (means and standarddeviations) Age at Post-mortem Diagnosis MMSE NART death Fixationinterval group score score (years) (months) (hours) CTRL, N = 20 28 11881 — — CVD, N = 18 25 116 81 — — AD, N = 20 15 100 74 — — FTD, N = 12 1697 71 — —Subjects:

Formalin-fixed brain tissue was sampled from 58 adults (20 normalcontrols, 18 MCI subjects, and 20 confirmed AD patients) who had diedbetween the ages of 59 and 101 years. (An additional set of youngercontrol subjects was also studied, as described in the next paragraph.)The healthy controls were free from neurological or psychiatricdiseases. The brains were part of the Thomas Willis Oxford BrainCollection, drawn from the OPTIMA cohort—a prospective longitudinalclinicopathological study of aging and cognitive decline. Subjectsunderwent cognitive testing at several time points in life. The resultsfrom the MMSE and national adult reading test (NART) were used in thepresent study. MCI subjects were identified as such by clinicalassessment in life and did not fulfil criteria for AD at death. ADpatients were confirmed with a Braak staging of V/VI at post-mortem.Cases were selected from the larger Thomas Willis collection to yieldcomparable group mean fixation times and ages at death as far aspossible, although pair matching was not possible. Demographicinformation per group can be found in Table 1. No comorbidity of alcoholor illicit drug misuse was detected in our sample's records. The mostcommon causes of death were bronchopneumonia and cardiac failure. Thisproject was carried out with approval of the UK National Research EthicsService, study code 07/H0605/69, and informed consent was obtained fromall subjects and family representatives. Brains were bisected andassigned a randomized code by a third party so that measurements couldbe made blind to diagnosis. Only the left cerebral hemisphere wasavailable for study, and this was fixed in 10% formalin. Samples fromdifferent brain regions were taken for confirmation of diagnosisaccording to the criteria of the Consortium to Establish a Registry forAlzheimer's Disease (CERAD) and assigned a Braak score. Brains thatshowed substantial signs of other pathology, including Creutzfeldt-Jacobdisease, Parkinson's disease, Lewy body disease, Huntington's disease,cerebrovascular disease, and brain tumours, were excluded.

CVD cases from the OPTIMA cohort were defined as having dementiaassociated with cerebrovascular disease including a combination of smallvessel disease, microinfarcts, atherosclerosis (in two cases there wasevidence of large vessel infarction) and a Braak NFT stage of I/II orless with absence or very sparse presence of neuritic plaques infrontal, temporal and parietal lobe neuropathological samples. FTD caseswere demonstrated to be TDP-43 positive with limited AD pathology (mostcases had no AD pathology, 3 cases had minor AD pathology (Braak stageI/II, no plaques) and one case had notable AD pathology (Braak stageV/VI, sparse plaques)). These cases also had no evidence of notablecerebrovascular disease, including no evidence of large vessel infarcts,microinfarcts, and absent or mild: atherosclerosis, small vesseldisease, and amyloid angiopathy. The subjects had received a diagnosisof fronto-temporal lobe dementia or, in three cases, a diagnosis offrontal lobe dementia with motor neuron disease-type inclusions(Parkinson's disease was excluded).

AD, MCI and control subjects were the same as those reported in previousstudies (Chance et al., Van Veluw et al.).

Neuropsychology:

Subjects underwent regular neuropsychological testing in life (typicallyevery 6 months). Three neuropsychological test scores were used to lookfor anatomical correlates in the present study. MMSE scores were used asa standard assessment for overall memory and cognitive decline that isin common clinical use. NART score was used because it has been shown tobe a reliable premorbid IQ estimation (McGurn et al. 2004). Anotherglobal cognitive decline assessment, Cambridge cognitive examination(CAMCOG) score was also considered but was not included in furtheranalysis because it so closely resembled MMSE score (Pearson's r=0.98;p\0.01) in all respects and it did not add anything further to theanalysis.

Tissue Sampling and Processing:

The regions of interest (ROIs) comprised five brain areas. Theseincluded two regions for which correlations between minicolumnorganisation and cognitive scores have been reported previously in AD(Van Veluw et al.), dorsolateral prefrontal cortex Brodmann's area 9(dIPFC, BA9) and the Planum Temporale (PT). Data from the primaryauditory region within Heschl's gyrus (HG) were also included, whichhave been reported previously for AD (Chance et al.). In addition, datawere collected from ventral/medial temporal lobe regions: theparahippocampal gyrus (PHG) and, for a subset of cases, the fusiformgyrus (Fusi).

An overall clinical neuropathological rating for plaque and tanglepathology was provided on the Braak staging scale. In addition aquantitative histological assessment was conducted to estimate moreprecisely the tangle density and plaque load in three regionsrepresentative of the three broad areas under investigation in thisstudy: medial temporal lobe, superior temporal lobe, and prefrontalcortex.

The dIPFC was sampled by taking blocks of tissue containing the superiorfrontal gyrus from the middle of the left hemisphere. The anterior andposterior limits of the dIPFC ROI were defined with reference tolandmarks on the medial surface of the hemisphere—the posterior limitwas formed by a vertical line drawn from the front edge of the genu ofthe corpus callosum and the anterior limit was vertical from theanterior apex of the paracingulate sulcus. A 5-mm thick sample block wasdissected from the dorsal brain surface within these bounds, descendinglaterally to the limit of the superior frontal gyrus. The PHG wassampled within an ROI as defined elsewhere (McDonald et al. 2000). Insummary, the limits of the ROI were given by the posterior boundary,defined as the most posterior part of the hippocampus, the anteriorboundary defined as the point where the hippocampus merges with theamygdala, and the superior boundary was the fusion between thehippocampus and the subiculum. The blocks were taken from randomizedpositions with respect to the anterior and posterior boundaries of bothROIs. For sectioning, blocks were cryoprotected by immersion in a 30%sucrose solution for 4 weeks, during which the solution was regularlyrefreshed. Then they were frozen and stored at −80° C. A cryotome wasused to cut 30-lm thick sections for slide mounting. For visualizingneurons (to measure minicolumn width) sections were Nissl stained withcresyl violet. Each ROI was analyzed on two non-contiguous slides(slides were separated by up to 5 mm within the ROI). Serial sectionsbetween the minicolumn sections were also taken to quantify the extentof plaques and tangles using methanamine silver stain and AT8immunohistochemistry.

Tissue Staining and Immunohistochemistry:

To demonstrate senile plaques in the dIPFC and PHG of the elderlysubjects (excluding the young control group), a methenamine silver stainwas applied to 30-lm thick sections heated in solution in the oven for90 min at 60° C. Cresyl violet (0.1%) was used for counterstaining. Toassess tangle pathology in both the dIPFC and PHG, 30-lm thick sectionswere reacted with phosphorylation-dependent antitau monoclonal mouseantibody AT8 obtained from Innogenetics. A primary antibodyconcentration of 1:1,500 was incubated for 60 min at room temperature.HRP rabbit/mouse secondary antibody was applied for 45 min, and stainingwas visualized using nickel-enhanced diaminobenzidine with hematoxylincounterstain.

Image Analysis

Plaque load was assessed and tangles were counted as described for aprevious study (Chance et al. 2011). In short, plaque load wascalculated by taking the percentage of intact tissue covered by plaques,by counting grid points on four digital photomicrographs of the ROIusing a standardised search pattern. Tangles were counted using multipleplacements of a 640 9 400 lm counting frame on live computerizedmicroscope images using an alternative search pattern. Tangle densitywas calculated per mm² from combined pyramidal cell layers III and V.Minicolumn width was quantified using semi-automated image analysis.This method and its validation have also been described in detailpreviously (Casanova and Switala 2005; Buxhoeveden et al. 2000). Insummary, minicolumn width is calculated from the combined width of thedense core region plus the associated peripheral neuropil-space aroundthe core. The minicolumn is taken to consist of both around the core.The minicolumn is taken to consist of both the core and its periphery.It is worth noting that, as in our previous reports (e.g. Chance et al.2006a, 2011; Di Rosa et al. 2009), the measure is effectively anestimate of centre-to-centre spacing of minicolumns. Although somestudies define width as only the width of the core, and spacing as onlythe space between cores, the designation of these boundaries tends to beless clear than the periodicity from centre-to-centre, which is themeasure most easily related to the wider literature (Peters 2010). Formeasurements, two sections from each ROI were used for sampling. Fourpictures were taken for each subject in each ROI, with each micrographcontaining a region about 1 mm² in area. Fields of view were selected bya random search pattern that excluded regions of high cortical curvaturesuch as the fundi of sulci or the apices of gyri [although minicolumnsare still clearly visible, high curvature affects cell distribution(Chance et al. 2004)]. Minicolumns are clearest in layer III, sominicolumn detection was centred on that layer. Photographs wereobtained through a 49 objective lens, with an Olympus BX40 microscope(FIG. 1) [more details can be found in Di Rosa et al. (2009) and Chanceet al. (2004)].

Statistical Analysis:

Statistical analysis was conducted using SPSS software (version 17.0).One-way ANOVAs were used to compare main effects for dIPFC and PHGplaques and tangles, dIPFC and PHG minicolumn width, andneuropsychological scores in the sample groups. Levene's test ofhomogeneity of variance was used to assess the equality of variances.Where a main effect was found, we looked at differences of means betweengroups using independent samples t tests. As post hoc tests we usedFisher's least significant difference (LSD), or Dunnett's T3 test in thecase of a non-homogenous distribution of the data. Paired samples ttests were used to compare pathology (plaques and tangles) in eachdiagnostic group and repeated measures ANOVAs were used to confirm thefindings as revealed by the t tests. Furthermore, the relationshipsbetween IQ and MMSE scores were compared using Pearson's correlationanalysis. The effect of age on minicolumn width was also assessed byPearson's correlation in normal aging subjects. An independent samples ttest was used to explore pathological differences in AD patients when wedivided the group in high and low IQ scores. Potential covariates wereidentified as age at death, fixation time, post-mortem interval, andtotal brain weight. Of these, brain weight (F=8.23; df=2, 55; p\0.01)and age at death (F=7.62; df=2, 55; p\0.01) differed between groups.Therefore, the influence of these two covariates was always tested byincorporating them into the ANOVAs.

Age is significantly different for both CTRL and CVD group compared toeither the AD or FTD group.

Results

Cerebrovascular Disease

Demographics:

Brain weight was significantly different between diagnostic groups(univariate ANOVA; F=6.1, df 3.72, P<0.01); brains were heavier incontrols than MCI and CVD, and all groups were heavier than the ADcases. Age at death was significantly different between diagnosticgroups (univariate ANOVA; F=6.3, df 3.75, P<0.01), mainly due to the ADcases having died at a younger age than cases in the other groups.

Post-mortem interval did not differ between groups (F=1.4, df 3.70,p=0.24) and fixation time did not differ between groups (F=0.8, df 3.75,p=0.53); therefore, these were not included as covariates in subsequentANOVAs.

Minicolumn Measures:

Minicolumn measures passed Kolmogorov-Smirnov tests for normaldistributions; therefore repeated measures ANOVAs were applied to thesedata. Pillai's trace criterion was used within these tests due to a lowBox's M-Test result for homogeneity of variance (P<0.05) (although thisdid not fall below the critical P=0.001 level).

There was a significant main effect of diagnosis (Pillai's trace, F=4.0,df 3.60, P=0.01) and a significant interaction between diagnosis andbrain region (Pillai's trace, F=3.7, df 12, 177, P<0.01) for measures ofminicolumn width. Post-hoc t-tests clarified the effects: minicolumnwidths in all brain regions were reduced in AD compared to controls(P<0.05 for all cortical regions). In CVD, minicolumn width was reducedin two brain regions; prefrontal cortex (t=2.3, df 35, P<0.05) andparahippocampal gyrus (t=3.6, df 32, P<0.01) compared to controls.Differentiating CVD from AD, minicolumn width was preserved in fusiformcortex in CVD (significantly wider than AD; t=5.4, df 32, P<0.01) andthere was a trend for preserved minicolumn width in the Planum Temporalein CVD (wider than AD; t=1.7, df 34, P<0.1). In these post-hoc tests ofthe separate brain regions, MCI cases did not have significantly reducedminicolumn width for any one region compared with controls (although ithas been shown previously that an overall reduction is detected in theseMCI cases when a combined statistical test is applied to multipleregions, including PT, PHG and PFC (Van Veluw et al 2012)). Compared toMCI, the AD cases had reduced minicolumn width in PFC (t=4.3, df 36,P<0.01), fusiform (t=5.0, df 33, P<0.01) and a borderline reduction inHeschl's gyrus (t=1.6, df 36, P=0.06), whereas minicolumns were thinnedenough in the PHG and PT that for these regions MCI cases did notsignificantly differ from AD.

Brain weight was a significant covariate (F=7.8, df 1.60, P<0.01) and sowas included in the rmANOVA (although it showed no other significantinteractions). Age was not a significant covariate (F=0.08, df 1.59,P=0.78) and did not significantly affect the other data interactions andso it was not included in the main rmANOVA.

Neuropathological Markers:

Measurements of plaques and tangles in the control, MCI and AD subjectsin this study have been reported previously for the three brain regionsinvestigated. However, further analysis is reported here for comparisonwith the two new groups of cases: CVD and (see below) FTD. Measurementsof plaques and tangles failed Kolmogorov-Smirnov tests for normaldistributions due to a floor effect where many subjects had values closeto zero in all diagnostic groups except AD (the AD group passed thistest for data from all three brain regions). Therefore, non-parametrictests were used for group comparisons:

Neuritic Plaques

The % cortical area covered by plaques (described here as ‘% plaquearea’) was significantly different between diagnostic groups for each ofthe superior temporal lobe, medial temporal lobe and prefrontal cortex(independent samples Kruskal-Wallis tests for all regions P<0.01).Post-hoc Mann-Whitney tests confirmed that AD subjects had greater %plaque area in all three brain regions compared to controls and to CVDcases. MCI was intermediate between these groups with higher plaque loadin the medial temporal lobe than both controls (U=34.0, Z=−4.2, P<0.01)and CVD (U=2.0, Z=−4.8, P<0.01) but no difference from controls or CVDin the prefrontal cortex or superior temporal lobe regions.

Overall, AD had elevated plaque load in all areas, whereas CVD hadrelatively low plaque load similar to controls. MCI looked intermediatewith elevated plaque load similar to AD in the medial temporal lobe butlower plaque load similar to CVD and controls in the other regions.

Neurofibrillary Tangles

The number of tangles/mm² was significantly different between diagnosticgroups for each of the superior temporal lobe, medial temporal lobe andprefrontal cortex (independent samples Kruskal-Wallis tests for allregions P<0.01). Post-hoc Mann-Whitney tests indicated that AD cases hada greater density of tangles in all three brain regions compared tocontrols, MCI and CVD (all P<0.01). CVD cases also had more tangles inall three regions compared with controls (all regions P<0.05), while MCIonly had more tangles compared with controls in one region: PHG (U=74.5,Z−3.2, P<0.01). The selective vulnerability of the PHG in MCI was alsonotable because for this region the density of tangles was greater thanin CVD cases as well (U=101.0, Z=−1.9, P=0.05), whereas for the othertwo regions tangle density was slightly greater in CVD (althoughstatistically not significant).

Fronto-Temporal Dementia

Unfortunately, ventral and medial temporal lobe tissue samples were notavailable for minicolumn analysis in the majority of FTD cases.Therefore, only regions PFC, PT and HG were included in the analysis ofFTD minicolumns. Minicolumn data passed Kolmogorov-Smirnov tests fornormal distributions and Box's M-Test result for homogeneity ofvariance, therefore rmANOVA was applied.

Demographics Including FTD:

Brain weight was significantly different between diagnostic groups(univariate ANOVA; F=12.0, df 4.85, P<0.01); brains were heavier incontrols compared with all groups, AD cases and FTD cases were lighterthan controls, MCI and CVD, and FTD cases weighed less than all othergroups. Age at death was significantly different between diagnosticgroups (univariate ANOVA; F=7.7, df 4.87, P<0.01), due to the AD and FTDcases having died at a younger age than subjects in the other groups.Fixation time did not differ between groups (F=1.4, df 4.87, p=0.24)and, therefore, was not included as a covariate in the main rmANOVA.Post-mortem interval also did not differ between groups (F=2.1, df 4.79,p=0.09), although because this was a weak trend (i.e. P<0.1) it wastested for significance as a covariate. PMI was not a significantcovariate (F=2.4, df 1.64, P=0.13) and as it did not markedly affect thesignificance of the other data interactions it was not included in themain rmANOVA. Age was also not a significant covariate (F=0.6, df 1.72,P=0.43). However, because the FTD subjects died at a significantlyyounger age than the other groups except for AD, its effect in thermANOVA was investigated and its inclusion did influence other datainteractions (see below). Brain weight was a significant covariate(F=5.7, df 1.73, P<0.05) and so was included in the rmANOVA (although itshowed no other significant interactions).

Minicolumn Measures:

There was a significant interaction between diagnosis and brain regionfor measures of minicolumn width (F=4.1, df 4.73, P<0.01), and a trendfor a main effect of diagnosis (F=2.2, df 4.73, P=0.08). Pillai's tracecriterion also revealed a trend for an overall difference between brainregions. However, inclusion of age as a covariate, while not asignificant covariate (see below), resulted in the loss of this trend(F=0.7, df 2.71, P=0.52), although the interaction between diagnosis andbrain region remained (F=2.4, df 8.144, P<0.05).

Post-hoc tests confirmed a pattern of contrasts distinguishing FTD fromthe other groups except AD. There was minicolumn thinning compared withcontrols in prefrontal (t=3.7, df 28, p<0.01) and temporal lobeassociation cortex (t=2.2, df 30, p<0.05) but not in primary auditoryregion HG. Compared with MCI and CVD the thinning in FTD was onlynotable for prefrontal cortex (MCI vs FTD: t=4.7, df 26, p<0.01; CVD vsFTD: t=2.4, df 25, p<0.05). Compared with AD the minicolumn widths inthese three brain regions did not differ from FTD cases, although therewas a trend for greater thinning in AD in the HG cortex (t=1.7, df 27,p=0.09).

Neuropathology:

As already established for group comparisons with cerebrovasculardisease, the % plaque area and the density of tangles/mm² also differedbetween diagnoses with the inclusion of the FTD data (all measuresP<0.01). Post-hoc tests identified that FTD had similar levels of thesepathological markers to CVD cases (although with a trend for a higherdensity of tangles/mm²; Mann Whitney U=74.5, Z=−1.7, p=0.09) and allmarkers were lower for FTD than for AD (all measures P<0.01). FTD caseshad lower levels of neuropathological markers in PHG than MCI cases(both plaque area, U=2.0, Z=−4.4, p<0.01, and tangle density, U=42.5,Z=−2.6, P<0.01) and lower plaque area in PT (U=50.0, Z=−2.5, p<0.05).Compared with controls, plaques and tangles were not different in FTDexcept for PHG where % plaque area was greater in controls (U=59.0,Z=−2.2, P<0.05).

Correlation Analysis

Overall correlations were tested across all subjects followed bypost-hoc tests to determine the extent of the relationships withindiagnostic groups:

Age:

For minicolumn width, only prefrontal cortex showed a correlation withage across all cases (r 0.31, p<0.01) (subjects who died at an older agehad wider minicolumns). No other regions showed this effect. However,within diagnostic groups the CVD cases differed from others in havingnegative relationships between age and both fusiform minicolumn width (r−0.68, p<0.01) and PHG minicolumn width (r −0.53, p=0.05) (minicolumnthinning in old age).

For neuropathological markers across all cases age was only negativelycorrelated with tangle density in STG (r −0.34, p<0.01). Furtherpost-hoc investigation confirmed that age was only correlated withtangle density in AD cases (older subjects had lower tangle density) inthe STG (r −0.65, p<0.01) and in PHG (r −0.64, p<0.01).

Donors who died at an older age also had higher MMSE (r 0.55, p<0.01)and IQ (r 0.36, p<0.01) scores. Within diagnostic groups therelationship with IQ score was positive for both the control (r0.50,p<0.05) and the AD (r 0.48, p<0.05) groups.

Brain Weight:

Heavier brains were associated with wider minicolumns for all brainregions across the total dataset. Within the control group, HG was theonly brain region in which this relationship held true (r 0.54, p<0.05)and no relationship was found for fusiform cortex or other associativebrain regions. The CVD cases differed from MCI and AD cases inexhibiting a positive relationship between PT minicolumn width and brainweight (r=0.53, p<0.05) and HG minicolumn width and brain weight(r=0.55, p=0.05), whereas MCI showed a positive relationship betweenfusiform minicolumn width and brain weight (r=0.55, p<0.05) and ADexhibited a similar trend (r=0.050, p=0.06).

For neuropathological markers across all cases, greater brain weight wasassociated with fewer neurofibrillary tangles in PHG (r=−0.30, p<0.01)and PFC (r=−0.23, p<0.05). No other correlations were found. Furtherpost-hoc analysis within diagnostic groups did not find correlationsbetween brain weight and any pathological markers.

Across all cases, donors with larger brains had higher MMSE (r=0.56,p<0.01) and IQ (r=0.40, p<0.01) scores. Post-hoc investigation withindiagnostic groups found that this relationship was only consistent inthe AD group (MMSE: r=0.57, p<0.01; IQ: r=0.52, p<0.02).

Minicolumns and AD Pathology:

Across all subjects and within each brain region % plaque area andtangle density were positively correlated with each other. Withindiagnostic groups % plaque area in the STG was correlated with % plaquearea in PFC. This was true for CVD cases (r=0.65, p<0.01) where therewas also a correlation between STG tangle density and PFC tangle density(r=0.70, p<0.01). The degree of pathology in MTL was less consistentlycorrelated with other variables, exhibiting no relationship in CVD,whereas in FTD the PFC plaques and tangles were highly correlated witheach other (r=0.95, p<0.01) and with MTL plaque area (PFC plaques:r=0.92, p<0.01; PFC tangles: r=0.98, p<0.01). In prefrontal cortex widerminicolumns were associated with lower % plaque area (as reportedpreviously; Van Veluw et al 2012). The other region which showed asimilar link between minicolumn width and pathology was fusiform cortexwhere narrower minicolumn width was associated with increased plaquesand tangles in the medial temporal lobe and the other regions (MTL andPFC). Within diagnostic groups these effects were mainly found in ADwhere increased % plaque area was associated with reduced minicolumnwidth in both the PHG (r=−0.47, p<0.05) and PFC (r=−0.47, p<0.05). Onenotable contrasting relationship was found in the FTD group where therelationship between minicolumn width and pathology in PFC was in theopposite direction (positive) for both plaques (r=0.70, p<0.05) andtangles (r=0.68, p<0.05).

Across all cases, minicolumn widths in PFC and PT were correlated witheach other (r=0.48, p<0.01). Within diagnostic groups this was found incontrols (r=0.54, p<0.05) as well as in MCI, AD and CVD. By contrast,although minicolumn widths in PHG and fusiform were also correlated witheach other across all cases (r=0.37, p<0.01), this was due tocorrelations in the dementia groups (CVD: r=0.66, p<0.05; AD: r=0.80,p<0.01) and was not found in controls (r=0.04, p=0.89) or MCI (r=0.39,p=0.13).

Neuropsychology and Neuropathology

Across all subjects, as reported previously for PFC, PHG, and PT (refs),wider minicolumns in fusiform cortex were correlated with highercognitive scores; MMSE (r=0.46, p<0.01) and IQ (r=0.28, p<0.05). Withindiagnostic groups this effect was mainly found in AD where minicolumnthinning in fusiform cortex was associated with lower MMSE (r=0.47,p<0.05) and lower IQ score (r=0.6, p<0.01). By contrast, in CVD, thisrelationship did not hold and the minicolumn width in the fusiformcortex and in all other brain regions was mildly (although notsignificantly) negatively associated with cognitive scores. For FTDthere were no apparent relationships between cognitive scores andminicolumn width in any regions.

For % plaque area and tangle density in PHG, STG and PFC (i.e. all ofthe regions where neuropath markers were measured) there weresignificant negative correlations with MMSE score across all cases.There were also negative correlations with IQ for tangle density in allregions, while for % plaque area the negative relationship was onlyclear for STG (r=−0.25, p<0.05). Within diagnostic groups relationshipsbetween higher tangle density and lower test scores (both MMSE and IQ)were found in the AD group, specifically related to the pathology in thePHG (MMSE: r=−0.62, p<0.01; IQ: r=−0.52, p<0.05), in the CVD group,specifically related to tangles in the STG (IQ: r=−0.52, p<0.05).

Example 2: Predictive Modelling

The same data used as in Example 1 but a different form of statisticalanalysis was applied, i.e. leave-one-out cross-validation which predictsthe status of one case on the basis of the model derived from all othercases and then repeats this process for all cases, resulting in a finalanalysis of the predictive value of the discriminant function modelderived from the whole dataset for all cases in the dataset. It is astandard form of analysis, conducted using SPSS statistical software inthis case.

Discriminant function analysis was used to generate predictive models tocategorise cases into diagnostic groups. This is of interest todetermine the differential diagnosis potential of multi-regionminicolumn data that may provide sensitivity and specificity estimatesas a target for neuro-imaging methods in living subjects. Discriminantfunction analysis was conducted with SPSS to investigate early diagnosispotential (controls, mild cognitive impairment (MCI) and Alzheimer'sdisease (AD)) and differential diagnosis (AD, cerebrovascular dementia(CVD), and frontotemporal dementia (FTD)).

Differential Diagnosis, AD Vs Cerebrovascular Disease:

A discriminant analysis was conducted using minicolumn widths from fivebrain regions: PFC, HG, PT, PHG, and Fusi to compare controls, CVD andAD. The resulting map with predictive group centroids and territories isshown in FIG. 7.

The analysis correctly classified 75% of the original group cases. PFC,Fusi, and PHG significantly differed between the groups (p<0.05 each).Function 1 had a canonical correlation of 0.61, with Wilks' Lambda 0.46,p<0.01, and Function 2 had a canonical correlation of 0.53, with Wilks'Lambda 0.72, p<0.01. A leave-one-out cross-validation analysis foundjust over 65% of cases correctly classified.

This model is interesting although it resulted in some overlap betweencontrols and each of the other diagnoses. The graphical analysisdemonstrates that group separation is promising, perhaps with theaddition of further brain region data. In addition, the controlterritory lying between AD and CVD indicates that the CVD data is not amildly affected intermediate between AD and controls but has a differentpattern of change from the other two groups.

Most interesting of all is that the AD and CVD groups are almostentirely separated. This is particularly important for differentialdiagnosis. Most of the inaccuracy in the model is due to overlap withcontrols. However, if the clinical decision of interest concerns thedifferential diagnosis of AD and CVD then a follow on discriminantanalysis looking at just these two groups is highly informative—such ananalysis was found to correctly classify 97% of the two diagnosticgroups. The canonical correlation was 0.87, Wilks' Lambda 0.24, p<0.001(Box's M was acceptable with a p-value >0.01) A leave-one-outcross-validation analysis found remarkably high predictive accuracy withjust over 93% of cases correctly classified. The only casemis-classified was a single AD case that was predicted to be CVD,leaving 100% correct classification of CVD cases. This model hasenormous potential for further application in imaging studies.

Early Detection (MCI):

A discriminant analysis comparing normally aged controls with mildlycognitively impaired cases (MCI) was conducted to estimate the potentialfor early detection before the diagnosis of dementia. Using the fivebrain regions mentioned above the analysis generated a model thatcorrectly classified 72% of the original grouped cases. Theleave-one-out cross validation test indicated correct classification of64%.

Classifying Frontotemporal Dementia:

A discriminant analysis of data from all regions resulted in theinclusion of too few members of the FTD group to be meaningful and suchan analysis became dominated by the AD and CVD data. However, it may benoted that the remaining cases of FTD were classified as CVD suggestingpotential separation from AD diagnosis which would be of great interestto assist clinical practice as, currently, differential diagnosis of FTDfrom AD is very challenging. Therefore a discriminant analysis wasfocused on the most meaningful clinical contrast—the contrast betweenFTD and AD—using the three brain regions that were available for themajority of these cases: PFC, HG, and PT. This analysis found that 71%of the original group cases were correctly classified with leave-one-outcross validation correctly classifying 68% of cases.

The correct differential prediction of AD cases was good at 90% withonly 10% mis-classified as FTD. However, the prediction of FTD groupmembership was poor with more than half mis-classified as AD. It islikely that greater accuracy would result from the inclusion of datafrom more brain regions including the regions that were missing here:Fusi and PHG.

Preliminary Data from Post-Mortem MRI Using Diffusion Imaging of Cortex:

This analysis extracted one of the measures that has potential as anindex of minicolumn structure in diffusion MRI (‘perpendiculardiffusion’). This measure was extracted from post-mortem images and thencompared with histological measurements from the same brain regionsfollowing dissection and microscope slide analysis.

FIG. 8A shows a graph of pilot data from post-mortem non-dementia brains(including controls, MS and autism)—wider minicolumns are associatedwith a lower perpendicular diffusion measure. The prediction for AD isthat minicolumn thinning will lead to an increase in the perpendiculardiffusion measure.

FIG. 8B shows our recent pilot post-mortem imaging reveals an increasedperpendicular diffusion measure in dementia consistent with minicolumnthinning (p=0.05, n=4 AD vs 4 controls).

FIG. 8C: the DTI biomarker shows a graded effect reflecting the degreeof AD pathology—values increase with greater severity of AD pathology.(Data are mean values for 4 control subjects and individual sub-regionsvalues from 4 probable AD brains—sub-regions PHG, HG, and PT show acharacteristic pattern of differences).

Example 3: Data from In Vivo MRI Scanning—Using Mean Diffusivity

This data was extracted from previously gathered MRI data in anotherstudy which was not optimal for this analysis (lower resolution dataacquisition) but was intended to give a sense of potential for gatheringin vivo data. This provided mean diffusivity data (which is likely to bea less sensitive indicator of minicolumn organisation than the measuresmentioned above) from in vivo MRI of subjects in two diagnosticcategories: MCI and healthy aged controls.

A discriminant analysis was conducted on data gathered from a small setof brain regions involving PHG, HG, and Fusi. The statistical modelfound that 71% of the original cases were correctly classified with aleave-one-out cross validation accuracy of 58%. Although these modelsare not as effective as the post-mortem MCI categorisation it is highlylikely that they would improve if further work was done to acquirehigher resolution in vivo data using the a more promising signal markersuch as ‘perpendicular diffusion’.

Pilot in vivo cortical diffusion data (mean diffusivity) from 6 subjectsshows patterns within single subjects that are more similar withingroups than between groups and are not only dependent on groupstatistics (see FIG. 9). The strongest signature for optimal sensitivityand specificity should be predicted by the post-mortem microanatomicalpatterns described above. Each graph shows cortical diffusivity (MD) for5 regions from a single subject. Each pair of graphs shows a similarpattern that differs from the patterns in the other rows. Top row:graphs from 2 Control subjects, Mid row: graphs from 2 MCI subjects,Bottom row: 2 AD subjects. The PHG feature in the pattern (orangecontrast) differentiates controls from MCI, the Fusi feature (yellowcontrast) differentiates AD from MCI. In addition, most values increasefrom control to AD.

Example 4: Diagnosis of Alzheimer's Disease

An example of a multi-region analysis of cortical diffusion data from asingle control and single AD case with a list of brain regions is shownin FIG. 11. Some example regions of interest for differentiatingdiagnoses are circled.

Data from an in vivo comparison of 18 AD and 18 control subjects isshown in FIG. 12. This shows a combination of angle of minicolumnardeviation with volume segmentation data summarised for whole brain.Clear separation of the groups is illustrated with only a singleanomalous control case found in the large separation zone delineated bydashed lines.

Example 5: Diagnosis of Autism Spectrum Disease

A comparison of in vivo data on autism and controls using one of the newDTI measures related to minicolumn angle of deviation is shown in FIG.13.

The invention claimed is:
 1. A computer-implemented method of obtainingan indication of the presence of a cognitive disorder or a trait of saiddisorder in a subject, the method comprising the steps of comparing: (a)one or more diffusion MRI measurements of minicolumn-based parametersobtained from a cortical grey matter of the subject's brain, or valuesderived therefrom; and (b) the corresponding measurement(s) or value(s)obtained from a control subject without a cognitive disorder, whereinthe minicolumn-based parameters are one or more parameters selected fromthe group consisting of minicolumn width, minicolumn spacing, axonalfibre bundle width, axonal fibre bundle spacing, dendritic fibre bundlewidth, dendritic fibre bundle spacing, minicolumn core width, andminicolumn peripheral neuropil space, wherein if the measurements orvalues obtained in step (a) are one which is positively correlated ordirectly proportional to the likelihood of the subject having acognitive disorder or a trait of said disorder, an increase in themeasurements or values obtained in step (a) compared to thecorresponding measurement(s) or value(s) in step (b) is indicative ofthe subject having a cognitive disorder or a trait of said disorder; andwherein if the measurements or values obtained in step (a) are one whichis negatively correlated or inversely proportional to the likelihood ofthe subject having a cognitive disorder or a trait of said disorder, adecrease in the measurements or values obtained in step (a) compared tothe corresponding measurement(s) or value(s) in step (b) is indicativeof the subject not having a cognitive disorder or a trait of saiddisorder.
 2. A method as claimed in claim 1, wherein the diffusion MRImeasurement is perpendicular diffusivity, mean minicolumn diffusivity,radial diffusivity, minicolumn width, fractional anisotropy, grey matterdensity or angle of columnar deviation.
 3. A method as claimed in claim1, wherein the cognitive disorder is a mental health disorder thataffects learning, memory, perception and/or problem solving.
 4. A methodas claimed in claim 1, wherein the cognitive disorder is a form ofdementia.
 5. A method as claimed in claim 1, wherein the cognitivedisorder is selected from the group consisting of Alzheimer's Disease(AD), cerebrovascular dementia (CVD), mild cognitive impairment (MCI),frontotemporal dementia (FTD), dementia with Lewy Bodies (DLB), autism,an autism spectrum disorder, multiple sclerosis (MS), epilepsy,amyotrophic lateral sclerosis (ALS), Parkinson's disease, schizophrenia,bipolar disorder, dyslexia, Down's syndrome, Huntington's disease, priondisease, depression, obsessive-compulsive disorder and attention deficithyperactivity disorder (ADHD).
 6. A method as claimed in claim 1,wherein the minicolumn-based parameter measurements are obtained fromone or more, two or more, three or more, four or more, five or more, sixor more, seven or more, or eight or more different regions of the brain,or from the whole brain.
 7. A method as claimed in claim 1, wherein theminicolumn-based parameter measurements are obtained from or derivedfrom one or more regions or layers of the brain, or from cortical layer3, cortical layer 5, or cortical layers 4-6.
 8. A method as claimed inclaim 1, wherein the minicolumn-based parameter measurements areobtained from or derived from one or more brain regions selected fromthe group consisting of parahippocampal gyrus (PHG), fusiform gyrus(Fusi), dorsolateral prefrontal cortex area 9 (dIPFC), Heschl's gyrus(HG), planum temporale (PT), inferior parietal lobule (IPL), middletemporal gyrus (MTG), the primary visual cortex (V1; area 17),orbitofrontal cortex and the primary motor cortex; or from the wholebrain.
 9. A method as claimed in claim 1, wherein the cognitive disorderis Alzheimer's Disease (AD) and wherein the minicolumn based parametermeasurements are obtained from or derived from one or more brain regionsselected from the group consisting of: (i) the banks of the superiortemporal sulcus, entorhinal, isthmus cingulate, lateral occipital,lateral oribitofrontal, middle temporal, parahippocampal,parstriangularis, pericalcarine or posterior cingulate region of theleft-hand cortex; and (ii) the banks of the superior temporal sulcus,cuneus, entorhinal, middle temporal, parahippocampal, paracentral orposterior cingulate region of the right-hand cortex.
 10. A method asclaimed in claim 1, wherein the cognitive disorder is Alzheimer'sDisease (AD) and wherein the minicolumn based parameter measurements areobtained from or derived from the whole brain.
 11. A system or apparatuscomprising at least one processing means arranged to carry out the stepsof a method as claimed in claim
 1. 12. A carrier bearing softwarecomprising instructions for configuring a processor to carry out thesteps of a method as claimed in claim 1.